1. Field of the Invention
The present invention relates to a ball screw apparatus, and more particularly to a ball screw apparatus including a dust cap or dustproof device easily and readily attached to the ball nut for suitably shielding the side or end portions of the ball nut and for preventing the dust or dirt from entering into the space between the ball nut and the screw shaft.
2. Description of the Prior Art
Typical ball screw apparatuses or devices comprise two movable members, such as a ball nut and a screw shaft rotatably engaged with each other and rotatable or movable relative to each other, and a number of ball bearing elements disposed between the two movable members for facilitating the sliding or rotational movement between the two movable members.
For example, U.S. Pat. No. 7,278,333 to Kato et al. discloses one of the typical ball screw devices comprising a ball nut pivotally or rotatably coupled onto or threaded with a screw shaft, and a number of loaded ball bearing elements disposed between the screw shaft and the ball nut for facilitating the movement between the screw shaft and the ball nut.
In operation, the screw shaft and the ball nut may rotate relative to each other and may also rotate relative to the ball bearing elements in a great speed such that the space between the ball nut and the screw shaft should be kept clean and should prevent the dust or dirt from entering into the space between the ball nut and the screw shaft and should prevent the ball bearing elements from being damaged by the dust or dirt.
In order to suitably seal the side or end portions of the ball nut, one or more seal rings are required to be engaged into the side or end portions of the ball nut and engaged with the screw shaft for suitably blocking the side or end portions of the ball nut and for preventing the dust or dirt from entering into the space between the ball nut and the screw shaft.
However, the contact or engagement between the seal rings and the ball nut and the screw shaft may increase the friction between the ball nut and the screw shaft, and the seal rings may be easily worn out after use, and the seal rings may not be easily and quickly replaced with the new ones when the seal rings have been worn out or damaged.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages of the conventional ball screw apparatuses.